Maternity Nursing: cram pack

Formula sheets, the key method steps for every topic and 6 practice problems, with full solutions at the back.

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1Formulas and methods

Maternity & obstetric nursing

Method

  1. Place the woman in time: weeks of pregnancy, stage of labour or day after birth, and decide what is normal at that point.
  2. Look for the patient in danger: the mother, the fetus or the newborn, or more than one of them.
  3. Link the finding to its cause: VEAL CHOP for decelerations, the four Ts for bleeding, BUBBLE-HE after birth.
  4. Choose the action that improves blood flow and oxygen first (side-lying, stopping oxytocin, fundal massage), then escalate.

Dosage calculations

Dose from strength
volume = dose / strength
Weight-based dose
dose = mg/kg × body weight
Tablets
number = dose / tablet strength
Units
1 g = 1000 mg, 1 mg = 1000 mcg

Method

  1. Convert the ordered dose and the stock strength to the same unit.
  2. Use desired over have times quantity: (D/H) × Q.
  3. For weight-based doses, multiply by the weight in kg first, then divide the daily dose by the number of doses.
  4. Estimate first and check that the answer is reasonable.

IV infusion rates

Pump rate
mL/h = volume (mL)/time (h)
Drip rate
drops/min = volume (mL) × drop factor / time (min)
Infusion time
time (h) = volume (mL)/rate (mL/h)

Method

  1. Pump rate in mL/h: volume divided by time in hours.
  2. Drip rate in drops/min: volume × drop factor divided by time in minutes.
  3. For time remaining: volume left divided by the rate.
  4. Round as the question or the equipment requires.

2Practice problems

1.Maternity & obstetric nursingMedium

On day 1 after birth, a woman's white cell count is mildly raised and she has no symptoms. How should this be interpreted?

  1. AIt shows she is dehydrated
  2. BIt means she has leukaemia
  3. CIt can be normal soon after birth
  4. DIt proves she has an infection
2.Maternity & obstetric nursingHard

A woman says she was told her non-invasive prenatal test (cell-free DNA) is "high chance" for trisomy 21. Which statement by the nurse is accurate?

  1. AThe result is diagnostic and the baby definitely has trisomy 21
  2. BA high-chance result means the test should simply be repeated at birth
  3. CThe test analyses fetal cells from the amniotic fluid
  4. DIt is a screening test, so a diagnostic test is offered to confirm it
3.Dosage calculationsMedium
024681010 mL

A child weighing 40 kg is prescribed 3 mg/kg of a drug. The stock solution contains 20 mg/mL. Draw up the dose: what volume V do you give?

40 kg3 mg/kg20 mg/mL
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 0.88 mg. The ampoule contains 4000 micrograms per mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

0.88 mg4000 mcg/mL
V = mL
5.IV infusion ratesMedium
250 mL20 gtt/mL4 h? gtt/min

Infuse 250 mL over 4 hours with a giving set of 20 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

250 mL4 h20 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1000 mg50 mL15 mL/h? mg/h

A bag contains 1000 mg of a drug in 50 mL and runs at 15 mL/h. How many milligrams per hour D does the patient receive?

1000 mg/50 mL15 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · It can be normal soon after birth

Why this is the answer

Leucocytosis is common in labour and the early postnatal period. It must be interpreted with clinical signs such as fever, pain and lochia changes rather than on its own.

Answer

C · It can be normal soon after birth
2.Maternity & obstetric nursing

Answer: D · It is a screening test, so a diagnostic test is offered to confirm it

Why this is the answer

Cell-free DNA testing analyses placental DNA in the mother's blood. It is very accurate but remains a screening test, so a high-chance result is confirmed by chorionic villus sampling or amniocentesis.

Answer

D · It is a screening test, so a diagnostic test is offered to confirm it
3.Dosage calculations

Answer: V = 6 mL

Drawing up a dose: volume = (prescribed dose/stock strength) × stock volume. Convert to the same units first, then check that the volume fits the syringe and lands on one of its graduations.

Dose from body weight

D = 3·40 = 120 mg

Volume

V = 120/20 = 6 mL

On the syringe

On this 10 mL syringe every small line is 0.2 mL.

Answer

V = 6 mL
4.Dosage calculations

Answer: V = 0.22 mL

Drawing up a dose: volume = (prescribed dose/stock strength) × stock volume. Convert to the same units first, then check that the volume fits the syringe and lands on one of its graduations.

Same units

0.88 mg = 880 mcg

Volume

V = 880/4000 = 0.22 mL

Answer

V = 0.22 mL
5.IV infusion rates

Answer: R = 21 gtt/min

Infusion rates: a pump is set in mL/h = volume/time in hours. A gravity drip is counted in drops per minute: gtt/min = volume (mL) × drop factor (gtt/mL)/time (min). The drop factor is printed on the tubing package: macrodrip sets deliver 10, 15 or 20 gtt/mL (blood sets often 10 gtt/mL in the US, 15 in the UK) and microdrip sets 60 gtt/mL. Always use the drop factor the question or package gives.

Time in minutes

4·60 = 240 min

Drip rate

R = 250·20/240 = 20.83 ≈ 21 gtt/min

Answer

R = 21 gtt/min

At the bedside you round to the nearest whole drop: 21 gtt/min.

6.IV infusion rates

Answer: D = 300 mg/h

Infusion rates: a pump is set in mL/h = volume/time in hours. A gravity drip is counted in drops per minute: gtt/min = volume (mL) × drop factor (gtt/mL)/time (min). The drop factor is printed on the tubing package: macrodrip sets deliver 10, 15 or 20 gtt/mL (blood sets often 10 gtt/mL in the US, 15 in the UK) and microdrip sets 60 gtt/mL. Always use the drop factor the question or package gives.

Concentration

1000/50 = 20 mg/mL

Dose rate

D = 20·15 = 300 mg/h

Answer

D = 300 mg/h

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